A
new Moon will keep skies dark for a display that Cooke and
others say could top 140 meteors per hour. According to the
International Meteor Organization, maximum activity should
occur around 12:10 a.m. EST (0510 UT) on Dec. 14th. The peak
is broad, however, and the night sky will be rich with Geminids
for many hours and perhaps even days around the maximum.

Right:
A flurry of Geminids in Dec. 2008 recorded by an all-sky camera
at the Marshall Space Flight Center. In

, note the circular halo that forms around the Moon
as it arcs across the sky; that is caused by ice crystals
in high clouds. [more]

Cooke
offers this advice: "Watch the sky during the hours around
local midnight. For North Americans, this means Sunday night
to Monday morning."

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Researchers
are interested to see what the Geminids do in 2009. The shower
has been intensifying in recent decades and they wonder if the
trend will continue.

Geminids
are pieces of debris from a strange object called 3200 Phaethon.
Long thought to be an asteroid, Phaethon is now classified
as an extinct comet. It is, basically, the rocky skeleton
of a comet that lost its ice after too many close encounters
with the sun. Earth runs into a stream of debris from 3200
Phaethon every year in mid-December, causing meteors to fly
from the constellation Gemini:

When
the Geminids first appeared in the late 19th century, shortly
before the US Civil War, the shower was weak and attracted
little attention. There was no hint that it would ever become
a major display.

But
now it has. "The Geminids are strongâand getting stronger,"
says Cooke, who has prepared a plot showing how the shower
has intensified since its discovery:

What's
going on? Jupiter's gravity has been acting on Phaethon's
debris stream, causing it to shift more and more toward Earth's
orbit. Each December brings a deeper plunge into the debris
stream.

Meteor
expert Peter Brown of the University of Western Ontario (UWO)
says the trend could continue for some time to come. "Based
on modeling of the debris done by Jim Jones in the UWO meteor
group back in the 1980s, it is likely that Geminid activity
will increase for the next few decades, perhaps getting 20%
to 50% higher than current rates."

A
50% increase would boost the Geminids to 200 or more meteors
per hour, year in and year out. "That would be an amazing
annual display," says Cooke.

Moreover,
says Brown, "the proportion of large, bright Geminids
should also increase in the next few decades, according to
Jones' model." So the Geminids could turn into a "fireball
shower."

Brown
cautions that "other models of the debris stream come
to different conclusions, in some cases suggesting that Geminids
will decrease in intensity in the coming decades. We understand
little about the details of the formation and evolution of
Phaethon's debris despite many years of efforts."